Are Radon Levels Higher in Winter or Summer?

Radon in Winter vs. SummerIf you’ve performed a radon test in your home, you may be wondering: does it matter when I test? Are radon levels higher in winter or summer? If you conducted a short-term radon test in the spring or summer and your home passed, you may want to think about conducting another test this winter. Radon levels can vary by season, with the highest levels typically occurring during the months that we heat our homes. That means that even if your home’s radon was below the EPA’s suggested action level of 4.0 picocuries per liter of air during the warmer months, it could be above that level during the winter.

Why Are Radon Levels Higher in Winter?

There are a few different answers to what can affect a radon test in the winter:

The Stack/Chimney Effect

You probably remember learning that warm air rises because it becomes less dense as it heats up. When you heat your home in the winter, the hot air escapes through the top of the house, and more air must be pulled in to equalize the pressure. The air can come from the soil below your house, potentially rising through the foundation, plumbing pipes, or the sump pump pit. Unfortunately, radon gas can come with that air.

A Snowy Barrier

Residents of Chicagoland and the rest of Illinois are pros when it comes to navigating snowy winter weather. However, even if the snow doesn’t interfere with your daily activities, it may affect the level of radon in your home. When there’s snow on the ground surrounding your house, it can create a layer of water or ice next to the soil that creates a barrier and traps radon underneath. Since the radon can’t escape through the soil outside of the house, it’s more likely to be pulled into the soil under your house and through your foundation.

A Sealed Home

Many of us are used to opening our windows on summer nights to help our houses cool down. By leaving your windows open, you can help dilute the radon gas in your home. Conversely, when you keep your windows sealed during the winter, the radon gas in your home can become more concentrated.

Other Factors

Seasonal variation isn’t the most influential factor when it comes to changes in radon levels.  Radon comes from the decay of radium in the soil, so a change could be caused by an increase or decrease in the amount of radium that has become ripe to decay into radon.  Radon also enters a home by riding on the soil gas that pushes through a concrete foundation, and at various times, the pressure of this soil gas can be lower or greater,  greatly affecting radon levels in the building.

Radon Mitigation Systems: Reducing Radon All Year

It can be frustrating to find out that your home’s radon levels might be higher in winter, especially since you’re probably spending more time indoors at this time of year, increasing the duration of your radon exposure. Fortunately, there is something you can do about this problem. Start by testing your home, and if it tests high, mitigate right away.  If a summer test reveals low radon levels, test again in the winter. If you find that your radon levels are above 4.0pCi/L, contact DuPage Radon Contractors and ask about our radon mitigation systems to reduce your radon levels all year long.

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